1. Field of the Invention
The present invention relates to a method for priming a blood tubing set which comprises a venous and an arterial line.
2. Description of the Related Art
Blood tube sets of this type are used in extracorporeal blood therapies, e.g. in hemodialysis, and form the extracorporeal blood circuit in this process. As a rule, disposable articles are used as the arterial and venous lines which are packed in a sterile manner and have to be filled and flushed prior to the treatment. This filling and flushing of the blood tubing set, called priming, serves the avoidance of a contact of the blood with air in the extracorporeal therapy as well as the cleaning of the blood tubing set and of the dialyzer or dialysis filter. For this purpose, the arterial and the venous lines are filled with a priming liquid, i.e. with a physiological solution, and thus deaerated after they have been connected to the dialyzer at the filter side. After the filling, the ends of the venous and arterial lines at the patient side are usually connected to one another directly or via a connection element so that the priming liquid can circulate in this circuit of arterial line, dialyzer and venous line until the patent is connected to the system. After the connection of the patient, the priming liquid is displaced by the inflowing blood such that a possible contact of the blood with air is reduced to a minimum. In this connection, the volume circulating in blood tubing set is, however, fixedly predetermined by the volume of the blood tubing set so that it can be too small to achieve a sufficient cleaning and deaerating effect depending on the sterilization procedure and/or on the production filter or the production fillers of the filter used. In addition the reconnection of the connections and the application or opening and closing of the valves are prone to operating errors of the dialysis nurse.
A priming method is furthermore known from U.S. Pat. No. 4,955,508 in which a bag with priming liquid and having at least two chambers is used. In this connection, a first chamber is filled with liquid and has two separate inlets which are arranged at the bottom of the bag. The second chamber is empty and only has one inlet. For the filling of the blood tubing set, the arterial line of the blood tubing set is now connected with one of the inlets of the full chamber while the venous line is connected to the inlet of the empty chamber. The liquid from the full chamber thus flows into the blood tubing set and is pumped from there into the empty chamber so that the blood tubing set is filled and flushed. Then the venous line is detached from the inlet of the second chamber and connected to the second inlet of the first chamber, whereupon the priming liquid circulates through the first chamber. If the consumed priming liquid should be replaced by fresh priming liquid before connection to the patient, one of the lines must in turn be removed and be connected to the inlet of a third chamber. A large liquid volume thus admittedly results which can circulate in the blood tubing set and the cleaning effect of the process can thus be increased. However, this is substantially predetermined by the amount present in the bag so that it cannot be adapted to the actually required amount. At the same time, however, a plurality of connection procedures are necessary which can lead to operating errors and additionally include the risk of contamination of the blood tubing set. In addition, mix-ups can occur due to the plurality of different connections on the bag. The transport and other procedures such as the sterilization of the bags are also complicated since the latter are filled with liquid.